High-frequency apparatus



April 5, 1949. J. R. WO ODYARD ET AL 2,465,067

HIGH-FREQUENCY APPARATUS 3 Sheets-Sheet 1 Filed Dec. '7, 1942 J. R. WOODYARD 4 INVENTORS: W. W. HANSEN TTORNEY 5 Shets-Sheet 2 J. R. WOODYARD fi fl INVENTORS'. W. W. HAN SEN ATTORNEY April 5, 1949. J, R. WOODYARD ET AL HIGH-FREQUENCY APPARATUS Filed Dec. 7, 1942 April 5, 1949. J. R. WOODYARD ET AL 2,466,067

HIGH-FREQUENCY APPARATUS 3 Sheets-Sheet 5 Filed Dec. 7, 1942 FIG. 5

FIG. 7

IIIIIII FIG-6 INVENTORS: W. W. HANSEN BY J. R. WOODYARD ATTORNEY Patented Apr. 5, 1949 UNITED STATES PATENT OFFICE HIGH-FREQUEN CY APPARATUS John R. Woodyard and William W. Hansen, Garden City, N. Y., assignors to The Sperry Corporation, a corporation of Delaware Application December 7, 1942, Serial No. 468,307

6 Claims.

ated grid structure in the form of figures of revolution about various axes, so that the oathode and grid areas are made relatively large without changing the resonating characteristics. Some of these structures are shown in United States Letters Patent No. 2,259,690 in which we are co-inventors.

The present invention is an improvement over the development represented by said patent and is especially directed to velocity modulated electron beam devices for high power operation wherein the resonator, grid and cathode structures preferably comprise figures of revolution in special highly eflicient association with a new arrangement for passing the electron beam through the resonator field.

It is therefore a major object of our invention to provide an ultra high frequency device of the velocity modulated electron beam type having novel internal construction and unusually efiicient operational characteristics.

A further object of the invention is to provide a. novel high frequency device of the velocity modulation type wherein a hollow resonator means is arranged about an axis and an electron beam is projected transversely of that axis through the field produced by the resonator.

,A further object of the invention is to provide a novel ultra high frequency hollow resonator device ofthe velocity modulation type arranged about an axis wherein an electron beam is transversely, preferably radially, projected through the device. The arrangement of the figure about the axis is preferably, but not essentially, that of revolution.

It is a further object of the invention to pro vide an ultra high frequency device of the velocity modulated electron beam type having a hollow resonator substantially in the form of a figure of revolution about an axis and an electron beam transversely projected through the figure.

Pursuant to this object the electron emitter may be shaped and located so as to surround or be. surrounded by the resonator as desired, and the electron stream is generally radially directed.

A further object of the invention is to provide an ultra high frequency device of the velocity modulation type having a resonator as a single tuned oscillation circuit and wherein thereinnovel arrangements are provided for ample cool-' ing of the device.

A further object of the invention is to provide a novel ultra high frequency device of the velocity modulated electron beam type wherein the relative capacities of the input and output electrode gaps are designed for improving the resonator characteristics.

A further object of the invention is to provide a high frequency velocity modulation device embodying a hollow resonator in the form of a figure of revolution about an axis and having novel associated grid and reflector arrangements.

Further objects of the invention will presently appear as the description proceeds in connectionwith the appended claims and the annexed drawings in which:

Fig. 1 is a perspective view partly in section through the axis of a preferred form of highfrequency device embodying the principles of the invention. The cathode here surrounds the resonator.

Fig. 2 is a perspective view partly in section of another embodiment of the invention wherein the cathode is centrally disposed Within the resonator.

Fig. 3 is a sectional view along the axis of a:

wherein the resonator fields for the input and output grids are individual so .that the device may be selectively employed as either an oscillator or amplifier.

Fig. 5 is a diagrammatic representation of the invention as embodied in a reflex device having an internal reflector.

Fig. 6 is a further diagrammatic representation of a reflex device according to the invention sim- J ilar to Fig. 5 but employing a resonator of different shape.

Fig. 7 is a diagrammatic representation of a" further embodiment of the invention as applied' to another form of resonator.

Fig. 8 is a diagrammatic representation of a still further embodiment of the invention similar to Fig. '7 but using a difierent manner of extracting output energy.

As will appear in the following detailed description, the device of the invention is primarily designed by developing, preferably by rotation about a selected axis, a generally toroidal structure having the same shape and "appearance "in cross-section as a simple velocity modulation device and having its grid sections substantially longitudinally disposed in the path -of;- general1y transversely or radially directed electrons from an external or internal cathode surface. The development of the figure about the axis is *not' limited to continuous revolution, such as a circle or ellipse, for example, but '.may include .discon-. tinuous revolution, such as a rectangle, as may be desired. In effect, the invention is chiefly concerned with what may be designated as a radial electron beam velocitymodulation device, as d-is tinguished from the usual velocity modulation devices embodying electron beamsdirected :axially of the hollowresonator.

Referring to'Fi'g. l the device of 'the'invention comprises a' hollow *metalcylinder having aside wall II and opposite end walls i2 and I3. "The interior-pf 'the cylinder is divided .into annular compartments or chambers'hl and i5 Joy-annular walls l6 and.l1, respectively, which extend the full length of the cylinder. Wall l l encloses a central cylindrical .compartment .123. -Wa'lls i I, I2, 153, I 6anid'll are :all :of copper or some good electrically conducting material :or may :be plated withza :gocd conducting material.

A ,acatho'de assembly comprising a suitable cannular support frame [9 carrying'an tannularl'hollow .ccathode :element .2! '''which presentsa uniform electron remitting surface 22 parallel :to wall [-6 :is :disposed inv :compartment I4. 'Frame is rigidly mounted on a series :of insulator .posts323 extending from wall 1 Land is o'f suitable :shape and size vto extend-overior focusing cathodezem'issiontoward the :electrodes. ,The electron1strea'm. from surface .22 isprojectedldirectly toward wall .Ihe cathodeis energized :by .a .coiled wire dilament 24 which .is heated to incandescence-bv energy from battery 25 through lead .26 andiree turn lead .21. .Leadslfi and .2! include terminals 28 and 29 extending through glass or like sins-u: lated gas-tight bushings 3| and 32111 wall H.

Walls vi 6. and 1221161 the. associated portions of walls .12 and i3 intersected thereby define the outer walls of the cavity resonator of the device. Within compartment l5,- an upstanding relatively thick metal wall 33 supports .a .hollow cylindrical metal tubularstructure comprising parallel' top and bottom walls .34 and .35 and parallel cylindrical walls.36 and 31. Wall33 provides a good heat conductive path .of .sufiicient capacity .110 cfficiently conduct the heat fromtheinternal walls 34,35, 36 and 31 tothe-exterior whereit .may be dissipated as by cooling. This .isan ap reciable advantage over the structures of Patent ..No..

shown inliig. 1, walls I6,..3.6, 31and lll'are. provided or formed with annular grid sections .38, 39, .40 and 4l',,respec,tively, aligned radially .with eachother and cathodesurface 22. While these grid sectionsare illustrated .as circumferentially spaced metal strips or bars having equal sized openings therebetween itis obvious that any suitable .form of grid segments may .be employed. Further, any convenienthunrbenof .thestripsor bars may be discontinuous as shown in the drawings, and only as many full length strips or bars as are necessary for proper support and good heat conduction from the grid and wall 22 need be provided. This provides a generally centrally apertured grid reducing interception of the electron stream at its central point.

:If desired, the grid strips or bars may be removable elements suitably mounted in slots formed in the respective walls supporting them as shown.

Grid-sections 38 and 39 have their openings aligned and serve as the beam-controlling or inrput :gri'dsof the-resonator, while grids 4i! and 4| also have their openings aligned and serve as the "beam-excited or output grids of the resonator. Input electrodes 38 and 39 are spaced apart materially less than are output electrodes 40 and i l, for reasons disclosed in said Patent No. 2,259,690, for most efficient operation of'this type of .-:device. .The :space between gridsections 39 and: 40 serves. as the :driftspaceof the resonator wherein the electrons-become velocity grouped.

..End wall i2 is -apertured at --42 for introducing a tuning element into resonator compartmentali. A metalcollar 43 .npstands from aperture 42 and is :closed by a glass. oover.-.44 .having :a .reentrant tubular gportion 4.5 projecting within compartment l5. =A=metal plunger-46 is slidably mounted in tubular guide 45,, --and the :displacementpf plunger 46 :is measurably -contr.o11ed..by the calibrated control knob "41.. .FKnob 41 .is mountedv .on the threaded vendof .the plunger shaft which in turn is slidably .butnon-rotatably mountedv in a suitable bracket asshown. vRotation of knob 41 produces translationonly ofplunger 46. .The

purpose of preventing rotation .is to eliminate:

tronspassing throug'h grid''fi andfins 51 extends axiallyof the device through the en'dwalls 1'2 and I3 and in contact with thesewal'ls-andifianges 51 and has suitable connec'tions'inot shown) for continuously circulating cooling fluid such 'as' water therethrough. I I

In operation'tl'ie 'uniform annular stream of electrons emitted by surface '22 passes first through input grids 38, 39 which initiate the-ve locity modulation-by causing alternate accele'ra tion and retarding --of the electrons, and then the streamepasses into' the drift space between grids 3'9 and '40 whichis proportioned to permit the bunching operation. "The bunched electron stream-then passes-throughoutput grids 4B,'-4l 'at which energy is derived from the velo city modulatedibeam andzdelivered :to maintain thecommonelectromagneticifield -within' compartment .15 I at resonantirequency. jJrBattery 54 connected to battery25 and :to wall 13 rovides the direct current.:driving voltage for the relectronzstream; and a. suitable gconcentric :line and antenna loop idevice 5.51s provided'for further extracting :ultra high frequency energy .from' the resonator .field.

In general, the energy conversion and :the phenomenon of velocity-modulatiomare the'ssame as inthe .usual velocity modulation device, sorthat further description 'ofthesame is unnecessary.

The general :advantagesbf this type ;of :device wherein the inesonator. field ;.is .common forzthe serves asac'ollector electrode for receiving elec-' input and'output grids are described in said Patent No. 2,259,690 to which reference is made for further detail. For simple devices of this type using a single tuned circuit, it has been found very difficult to remove heat from the interior of the device due to lack of heat conducting paths. In the invention, provision of a structure of revolution affords large grid areas for widely distributing the internal heat, and wall 33 is sufficiently thick to provide good heat conduction to the exterior where any suitable cooling such as an air blast may be employed.

Variation of the resonant frequency of resonator chamber 5 is accomplished by adjustment of knob 41 to change the displacement of plunger 45 within the chamber. The glass tubing 45 of course does not appreciably disturb the field within the resonator, but displacement of the metal plunger is effective upon the electromagnetic field.

Many of the electrons passing through final grid 4| are intercepted by the relatively fine Woven suppressor grid 48 which is connected by an insulated return lead 56 to the cathode or to a point between cathode and input electrode potential, thus returning electrons to the supply and improving the overall efiiciency of the device. Electrons passing through grid 48 and fins 5| are collected by pipe 53 where they give up their energy as heat to be radiated by the fins or conducted away by the coolant within the pipe. Grid 48 and fins 5| are of such nature as to intercept and thereby suppress the harmful effects of secondary emission of electrons from pipe 53. Grid 48 is cooled by radiation to compartment l8, which in turn is cooled by fins 5|, pipe 53 and radiation from the end walls.

The entire interior of the device :bounded by gas tight walls II, It and I3 is evacuated, and all lead-in or pipe connections are of such nature as to preserve the vacuum.

The above-described device is an efficient high power velocity modulation device having very large associated cathode and grid areas. In its preferred form as set forth, the resonator describes a continuous developed figure, preferably of revolution, which may be rectangular in crosssection, circular, or of any equivalent shape, about the central axis as noted in the objects of our invention. The invention is thus of sufficient scope to embrace the use of any generally toroidal structure of regular revolution or equivalent or similar disposition about an axis. The large exposed cathode surface 22 provides for maximum current output without increasing the current density of the surface, thereby enabling it to operate at relatively low and safe filament temperatures for high power output. Another advantage is that this is the only single tuned circuit resonator known to us which has an eflicient cooling system for extracting heat from the interior.

The embodiment of the invention illustrated in Fig. 2 is the same as Fig. 1 except that the cathode is disposed inside the figure of revolution defined by the resonator so that the electron stream is projected radially outwardly therefrom. For convenience in illustration, certain of the grid bars are not shown but are merely indicated by the dot-dash lines. Preferably the electrodes are as in Fig. 1. device are designated by the same numbers as in Fig. 1.

In Fig. 2, compartment I8 is the cathode compartment. The cathode assembly 5| is supported Corresponding parts of the from wall I2 by a pair of insulator posts 58, and the electrical leads supplying energy for heating the filament and introducing the accelerating voltage for the cathode are sealed in a gas tight insulating bushing in wall I2. As shown, cathode 51 is preferably of simple cylindrical form, although any desired shape presenting an outwardly emitting surface may be employed. The electron emission surface 59 of the cathode is annular, parallel to grid 4| and of considerable area. It projects a uniform annular stream of electrons through the resonator as above explained, with the exception that in Fig. 2 grids and 4| are the input grids while grids 38 and 39 are the output grids. Electrons which emerge from grid 38 strike annular collector Wall Hi, there giving up energy as heat to be radiated or conducted away by cooling coil 60.

The internal cathode of Fig. 2 is peculiarly efficient in that it enables very accurate direction and focusing of the electron stream. It further does not present all the special internal cooling problems inherent in Fig. 1, where all the elec trons are directed toward a common point, and its cathode area is sufficiently large to efficiently handle relatively high power. The device of Fig. l is more desirable however for very high power tubes.

Fig. 3 illustrates a radial device similar to Fig. 2 but having special arrangements for capacity loading the input grid circuit. bottom plates El and 62 are rigidly secured as by welding to a hollow cylindrical external body wall 63 which holds them in spaced relation. Bottom plate '62 is internally shouldered for seating an annular inner wall 64 which fits snugly within the inner periphery or upper plate 6| as shown. Plates BI and 52 and walls 53 and 64 define the outer walls of resonator chamber 55 40 of this device.

Within chamber is disposed an annular grid supporting a drift space member 66 having an upstanding integral rim 6'! mating with a cooperating groove in the bottom of plate BI, and rim 61 is secured as :by welding to plate SI for mounting member 66 in the resonator.

Member 66 comprises upper and lower annular plates 68 and 69 held together in spaced relation by inner and outer series of grid bars 10 and 1|, respectively. Preferably plates 68 and 69 are formed with spaced slots about their entire inner and outer circumferences for receiving the grid bars, which in turn are welded or similarly permanently secured thereto. As in Fig. 1, certain of the bars may be discontinuous at the grid centers to prevent interference with the passage of the central portion of the electron stream.

Inner wall 64 is formed with a grid section 72 having openings in alignment with grid The space between grids H and 12 is considerably smaller than the space between grid 10 and wall 63. The voltage across the output gap between electrode 10 and wall 63 is higher than across the gap between electrodes H and 12, the field intensity also being greater between the output electrodes.

The area of inner peripheral surface 13 of member 65 is parallel and coextensive with wall 64 and is purposely made very large as shown so as to increase the capacity space 14 in the input electrode circuit. This feature together with the relation between spacings of the input and output electrodes assures that a voltage node will exist in the field within the resonator approximately opposite support 61. This facili- Annular top and anemone tates tuningof the resonatorin-the'manner shown in. Fig. 1, which tuning effectively displaces such anode, by making the tuning adjustment less sensitive.

Cathode E5, of similar shape to that at Fig. 2, is supported centrally of the device by suitable means (not shown) in base 16. The electron stream from cathode I is velocity modulated during passage through the resonator, and the usual concentric transmission line and loop 55 is arranged to extract ultra high frequency energy from the field.

The upper end of wall 64 is formed with aseries of longitudinal slots I? so as to be expansible, and a suitable annular expansion ring I8 is inserted therein to retain wall'64 fixed in its seat. A cover 79 closes the top of the device, being secured thereto as by bolts 8| which when tightened compress a flexible sealing ring between the cover and the plate 6i. Cooling fluid coils 82 and 83 conduct heat away from the device during operation, wall 63 serving as the collector electrode. The interior of the device is exhausted and the vacuum maintained during operation.

Fig. 4 diagrammatically illustrates a high power radial device having an external annular cathode 2| similar to that in Fig. 1. As in Fig. 1, the resonator is in the form of a figure of revolution about the central axis but the input and output resonator circuits are maintained electrically separated so that the device may be used as an amplifier. This may be accomplished in Fig. 1 simply by providing a support wall similar to wall 33 but extending between walls I2 and 34, thus dividing the space between walls I6 and I! into two physically separate resonator chambers instead of the common chamber I5 of Fig. 1.

Referring to Fig. 4, inner and outer annular resonators 89 and 85 are concentric about their common axis. An annular drift space enclosure 86, which may be formed as in Figs. 1 and 3, extends between and projects into the resonators. Input grid sections 81 and 88, and outputgrid sections 89 and SI are transversely or radially aligned. The cathode and resonator arrangement are enclosed in an evacuated envelope as in Fig. 1.

Suitable individual tuning means 90 and 90', similar to that at 46 in Fig. l, are provided for resonators M and 85. Concentric antenna line connections 92 and 93' individual to resonators 84 and 85 are also provided, enabling the device to be used as an oscillator when they are. interconnected. The interior of Fig. 4 has the same water-cooled collector electrode 53 as in Fig. I, and also has the same grid 48 and heat radiant fins 5| for suppressing secondary electron emission as'in Fig. 1. Otherwise the device of Fig. 4 has the operation above explained.

Fig. 5 illustrates diagrammatically a section through the axis of a hollow resonator velocity modulation device having but a single: electrode gap and a reflector for returningvelocity grouped electrons through the gap.

Annular cathode 2I surrounds a hollow conductive member 92 which is preferably in the form of an annulus of revolution about axis A--A. Grid electrodes 93 and 94' are'provided in alignment on the outer cylindrical wall 95 and on the reentrant annular pole 90. An annular reflector having a continuous radially outwardly facing refleeting face 91 is suitably mounted to locate face 91in proper. location.

section illustrated, about axis BB.

Electrons inx-theradiallydirectedrannular beam emittedfrom surface 22 are alternately retarded" and accelerated in passing'through the gap. between electrodes: 93 and 94 so that they become velocity-grouped by the time they are returned by reflector 91 back through the electrode gap.= As the velocity-grouped electrons return through the. gap between electrodes 94 and93 they are in condition. to. give up energy to the field. Since these general principles of reflex operationare known, further detail is unnecessary. This em? bodiment as described demonstrates application of the invention to velocity modulation devices of the reflex type.

v Fig. 6 is similar to Fig. 5 but illustrates a reflex device wherein the resonator shell 98. is of some-- what different shape, being a figure 0f revolutionof the illustrated cross-section. Here grids 99* and I00 are aligned on the inner peripheral wall-- of hollow body 98 and the end of inwardly projecting reentrant annular pole IN, and reflector I02 is a relatively slender annulus suitably supported opposite grid 99. Annular cathode I03 is smaller than cathode 22; being suitably mounted close to grid I00. The operation of the device of Fig. 6 is similar to that of Fig. 5.

Fig. '7 illustrates another velocity modulation device according to the invention wherein thegenerally annular resonator b'ody I04 comprises a figure ofrevoluti'on of a simple hollow resonator body. of the frustro-conical cross-section illus= trated, about the axis B-B. Entrance and exit grid electrodes I05 and respectively, are formed in the cylindrical walls of" body I04; in-

radial alignment with annular cathode 2i and.

an annular collector electrode I061 Similarly Fig. 8' illustrates a further simple single chamber resonator body I01 formed by revolution of the generally frustro-conical-cross- Annular' cathode I08 is supported centrally in an opening of a cylindrical annular electrode I09 insulated from body I 01 by the insulating annulus I10" which also seals the opening III in the outer wall of the resonator body. The oscillating cir-' cuit is provided bythe two opposed electrodes comprising electrode I09 and the bottom wall'l I2 of body I01; A coupling loop '=Il3' is disposed inside the resonator and adapted for extractionof energy as desired.

Figs. '7 and 8 therefore illustrate application of the invention-to the type of velocity modulation device disclosed in United States Letters Patent No. 2,269,456 issued January 13, 1942, to- Hansen et al., and reference is made to that patent for further details of common operation. The general structure of these two figures is broadly coveredin copending application, Serial No. 474,621, filed" in the name of Russell H. Varian.

As 'many'changes could be made in the above construction and many apparently widely different embodiments of this invention could be made. without departing'from the scope thereof, it is intended that all'matter contained in the above; description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What'is claimed is:

1. An ultra high frequency device comprising a substantially annular hollow resonator having, a wall provided with an electron-permeable section, said resonator having an interior hollow member" surrounding a field-free electron drift space;- said liollow'member-"being surroundedby the electromagnetic field space of said resonator, and a cathode having an electron emission surface surrounding said resonator adjacent said electron-permeable section, electrons from said cathode after passing through the electronpermeable section of said resonator becoming velocity modulated within said resonator and before entering said interior hollow member, said hollow member having an electron-permeable section to admit the electrons thereinto to enable grouping of the electrons within said hollow member, said hollow member having a second electron-permeable section enabling the passage of the grouped electrons back into said resonator for eifecting an interchange of energy with the electromagnetic field thereof.

2. An ultra high frequency device comprising, a substantially annular hollow resonator adapted to have an oscillating electromagnetic field established therein, a cathode having an electron emissive surface surrounding said resonator and' adapted to project electrons into said resonator and through such field, a hollow interior member contained within said resonator and completely surrounded by the field space of said resonator and providing a field-free drift space for electrons, and means for collecting electrons located radially inwardly of said resonator, said electron collecting means having means for dissipating secondary emission electrons.

3. An ultra high frequency device of the velocity modulation type comprising, hollow annular resonator means having an outer annular wall and an inner annular wall located radially inwardly of said outer wall, said resonator means being provided with transverse openings in its outer and inner annular walls, cathode means located exteriorly of said resonator means for directing a stream of electrons radially inwardly through said openings, and an interior hollow member providing a field-free drift space for the stream of electrons, said interior hollow member having an electrode projecting outwardly therefrom opposing the inner wall of said resonator for forming therewith a condenser for increasing the capacity of the resonant circuit of the resonator thereby providing considerable efiective capacitance at said electrode.

4. High frequency electron discharge apparatus comprising a source of electrons, a cavity resonator having an outer enclosing wall adjacent said source and a hollow body supported therewithin, said wall and hollow body having electron-permeable portions defining a pair of electron-permeable gaps, voltage accelerating means electrically connected with said electron source and said resonator for projecting a stream of electrons from said source successively through said gaps, means positioned in the path of said electrons exteriorly of said resonator for collecting said stream of electrons after passage through said gaps, and suppressor means surrounding said collecting means for preventing return of secondary electrons from said collecting means to said resonator.

5. Apparatus as in claim 4, wherein said suppressor means comprises a grid interposed be tween said resonator and said collecting means, and means electrically connecting said grid to said source.

6. Apparatus as in claim 4, wherein said collector means comprises a series of conductive members substantially parallel to said electron stream for minimizing secondary electron emission and providing increased surface area for heat dissipation.

JOHN R. WOODYARD. WILLIAM W. HANSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,108,900 Peterson Feb. 22, 1938 2,151,765 Hollmann Mar. 28, 1939 2,170,219 Seiler Aug. 22, 1939 2,190,668 Llewellyn Feb. 20, 1940 2,216,170 George Oct. 1, 1940 2,224,649 Harris Dec. 10, 1940 2,289,846 Litton July 14, 1942 2,298,949 Litton Oct. 13, 1942 2,392,379 Hansen Jan. 8, 1946 

